To provide a fire spread prevention device which can prevent the spread of a fire generated in a lower story to an upper story even if a combustible resin pipe is employed as a drain down pipe in a building such as a high-rise dwelling, and to provide a drain piping structure.

The fire spread prevention device 1 has a body 14 and shielding members 15a, 15b which are all formed of incombustible materials. The body has an insertion hole 21 which can be attached to a connection auxiliary member 29 formed of the incombustible material for connecting a down pipe 4 having combustibility or thermoplasticity to the discharging side of a drain collecting pipe 3, or attached to the discharging side of the drain collecting pipe. When the body is mounted to the drain collecting pipe or the connection auxiliary member, each shielding member is movable or rotatable from a position that is radially located outside the down pipe to a position that blocks the insertion hole.